From ba41477c922ad4efab41a5f9300f576cc8a5cf8a Mon Sep 17 00:00:00 2001
From: Leo Ma <begeekmyfriend@gmail.com>
Date: Mon, 28 Aug 2017 09:37:03 +0800
Subject: [PATCH] Word search

Signed-off-by: Leo Ma <begeekmyfriend@gmail.com>
---
 079_word_search/Makefile      |  2 ++
 079_word_search/word_search.c | 66 +++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)
 create mode 100644 079_word_search/Makefile
 create mode 100644 079_word_search/word_search.c

diff --git a/079_word_search/Makefile b/079_word_search/Makefile
new file mode 100644
index 0000000..99bef24
--- /dev/null
+++ b/079_word_search/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test word_search.c
diff --git a/079_word_search/word_search.c b/079_word_search/word_search.c
new file mode 100644
index 0000000..54cae5d
--- /dev/null
+++ b/079_word_search/word_search.c
@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+static bool recursive(char *word, char **board, bool *used, int row, int col, int row_size, int col_size)
+{
+    if (board[row][col] != *word) {
+        return false;
+    }
+
+    used[row * col_size + col] = true;
+
+    if (*(word + 1) == '\0') {
+        return true;
+    }
+
+    bool result = false;
+    if (row > 0 && !used[(row - 1) * col_size + col]) {
+        result = recursive(word + 1, board, used, row - 1, col, row_size, col_size);
+    }
+
+    if (!result && row < row_size - 1 && !used[(row + 1) * col_size + col]) {
+        result = recursive(word + 1, board, used, row + 1, col, row_size, col_size);
+    }
+
+    if (!result && col > 0 && !used[row * col_size + col - 1]) {
+        result = recursive(word + 1, board, used, row, col - 1, row_size, col_size);
+    }
+
+    if (!result && col < col_size - 1 && !used[row * col_size + col + 1]) {
+        result = recursive(word + 1, board, used, row, col + 1, row_size, col_size);
+    }
+
+    used[row * col_size + col] = false;
+    return result;
+}
+
+static bool exist(char** board, int boardRowSize, int boardColSize, char* word) {
+    int i, j;
+    int len = strlen(word);
+    if (len > boardRowSize * boardColSize) {
+        return false;
+    }
+    bool *used = malloc(boardRowSize * boardColSize);
+    for (i = 0; i < boardRowSize; i++) {
+        for (j = 0; j < boardColSize; j++) {
+            memset(used, false, boardRowSize * boardColSize);
+            if (recursive(word, board, used, i, j, boardRowSize, boardColSize)) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+int main(int argc, char **argv)
+{
+    if (argc < 3) {
+        fprintf(stderr, "Usage: ./test word row1 row2...\n");
+        exit(-1);
+    }
+    printf("%s\n", exist(argv + 2, argc - 2, strlen(argv[2]), argv[1]) ? "true" : "false"
+);
+    return 0;
+}